CN101410266B - Grounding Structures for Vehicles - Google Patents

Abstract

A ground connection for a vehicle comprising a wheel (1), a sliding suspension for a wheel carrier relative to a support (10) connected to the vehicle, the suspension comprising a substantially vertical pillar (8) fixed to the wheel carrier, the degree of freedom of suspension of the wheel carrier relative to the support (10) being permitted by the movement of the pillar in the guide means (11) connected to the support, means for driving the wheel by a first rotary electric machine (15) mounted in the wheel, the first electric machine driving the wheel by means of reversible reduction means, the reduction means comprising a ring gear (16) fixed to the wheel and a drive pinion (17) connected to the first machine and defining a reduction ratio between the speed of rotation of the first machine and the speed of rotation of the wheel, the reduction ratio being greater than 10, said ground connection having no mechanical service brake.

Description

Grounding Structures for Vehicles

technical field

The invention relates to ground connections of motor vehicles. In particular it relates to grounding systems in which the vertical suspension uses slides and the propulsion of the vehicle uses electric motors, the slides and electric motors being embedded in the wheels.

Background technique

From patent application EP0878332 is known a grounding structure in which the degree of freedom of the wheel frame relative to the vertical suspension of the vehicle chassis is allowed by the movement of the vertical column fixed to the wheel frame in guides fixed to the support , the support itself is attached to the vehicle body. The ground structure also includes a rotating traction motor, reduction means connecting the traction motor to the wheels, disc brake means, suspension springs, motors for controlling the movement of the suspension and pivots to allow the wheels to steer. The construction of this ground structure effectively ensures all the functions provided.

It is an object of the present invention to provide a grounding structure of the above-mentioned type in which the balance between mass, stiffness and space requirements is significantly improved.

In particular, the mass of the grounding structure, especially of its non-suspended components, is an important aspect of the dynamic performance of the vehicle. The mechanical stiffness of the ground structure is also an important aspect. Insufficient rigidity can have a negative effect on the guiding qualities of the wheel plane, but also on factors detrimental to the service life of the elements of the ground contact structure, for example due to fatigue of the material, wear associated with friction due to deformation. It is understood that the space requirement is a particularly important feature, since the particular advantage of this type of ground contact structure is that all functions are integrated in the inner volume of the wheel.

Those of ordinary skill in the art know that these three characteristics (mass, stiffness, space requirements) are closely related to each other. Therefore, it can also be said that the present invention aims to provide a grounding structure of the type described above, for which at least one of the three aspects is significantly improved without necessarily compromising the other aspects.

Another object of the invention is that the maintenance of a grounding structure of the above-mentioned type can be considerably simplified.

Contents of the invention

The aforementioned objects are achieved by a grounding structure for a vehicle comprising: a sliding suspension for a wheel frame sliding relative to a support (10) connected to the vehicle, said suspension comprising a a substantially vertical column (8) of the wheel frame, the degree of freedom of the suspension of the wheel frame relative to the support (10) is allowed by the movement of the column in the guide means (11) connected to the support; and means for driving the wheel by means of a first rotating electrical machine mounted in the wheel, the first rotating electrical machine driving the wheel by means of a reversible reduction gear comprising a ring gear fixed to the wheel, and a motor connected to the first electrical machine The pinion is driven and defines a reduction ratio between the rotational speed of the first rotating electrical machine and the rotational speed of the wheels, said reduction ratio being greater than 10, said ground contact structure having no mechanical service brake.

Preferably, the reduction ratio is greater than 15, and also preferably, the reduction device includes two stages of reduction.

Preferably, said reduction means comprise a reduction gear cooperating on the one hand with a drive pinion and on the other hand with a ring gear fixed to the wheel. Also preferably, the reduction gear comprises two coaxial one-piece toothed wheels, the teeth of which are helical and oriented in the same direction.

Preferably, the axis of rotation of the first electric motor is parallel to the axis of rotation of the wheel.

Preferably, the drive pinion has helical teeth and is guided relative to the axis of the wheel independently of the shaft of the first electric machine.

Preferably, the guidance of the rotating assembly comprising the wheel and the ring gear is provided by a pair of rolling bearings which are fitted on the lugs of the wheel carrier.

Further preferably, the grounding structure further comprises a second rotary motor for controlling the movement of the suspension, the second motor being fixed to the guide; and a suspension pinion driven by the second motor, the suspension pinion Mates with a rack secured to the post. Furthermore, preferably, the axis of the column is positioned substantially on the center plane of the wheel and intersects the axis of rotation of the wheel.

Preferably, the ground engaging structure further comprises a pivot connection of the guide means guided relative to the support to allow steering of the wheel about a pivot axis, preferably substantially corresponding to the axis of the post.

The invention also relates to a vehicle comprising such a grounding structure, which also comprises means for absorbing electrical energy capable of absorbing the electrical energy generated by the first electric machine during braking.

Preferably, the absorbing means comprises an electrical resistor submerged in a bath of heat transfer liquid. It is also preferred that the absorbing means comprise means for storing electrical energy capable of storing a portion of the electrical energy generated by the first electric machine during braking.

Description of drawings

Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments. The accompanying drawings are as follows:

Figure 1 is a sectional view along a vertical plane along the axis of rotation of a wheel comprising a ground contact structure according to the invention;

Fig. 2 is a partially cut-away perspective view, in particular showing the reduction gear of this embodiment of the present invention;

3 and 4 are perspective views of the ground engaging structure according to the present invention, with wheels not shown, viewed from the outside of the vehicle. The reduction gear is clearly visible in Figure 3;

FIG. 5 is a top view of the grounding structure viewed from inside the vehicle;

Figure 6 is a partially cutaway perspective view of components for guiding and controlling the suspension of the ground contact structure according to the present invention; and

Figure 7 is a schematic illustration of an example of the structure and operation of an electrical device providing control of traction/braking of a grounding structure according to the present invention.

Detailed ways

Wheel 1 see figure. The wheel is assembled from a rim 2 and spokes 3. A tire 4 mounted on a rim 2 is shown. The wheel is mounted rotatably about its axis 5 on a wheel carrier 7 by means of rolling bearings 6 .

The drive power for the wheels is provided by means for driving the wheels comprising a rotating electric traction machine 15 mounted on the wheel frame 7 . According to an essential feature of the invention, the electric traction machine is also used to brake the vehicle. When "braking" is used in this context, the term is understood to mean the action of not only slowing down a vehicle while it is in motion but also bringing the wheels to a standstill by transmitting braking torque to the wheels to allow them to come to a quick and complete stop Do not move. This braking function is therefore completely different from the concept of recuperating energy (“regenerative braking”) well known in the field of electric vehicles, which cannot completely dispense with conventional braking devices.

The essential feature of the ground contact structure according to the invention is that it has no mechanical foot brakes, ie no conventional braking means using friction, such as disc brakes or drum brakes. By "foot brake" is understood a brake that provides braking while the vehicle is in motion. This service brake differs from a parking brake which itself has the function of immobilizing the vehicle after it has come to a standstill, for example without a driver. This stationary function does not require any special ability to dissipate energy. It will therefore be appreciated that a grounding structure according to the present invention may include a mechanical parking brake, although it does not include a mechanical service brake.

The rotating electric traction machine 15 is also a rotating electric braking machine at the same time. Therefore, it itself ensures the braking and driving of the wheels. That is why in this application, depending on the context, the terms "tractor", "tractor/brake" or "first machine" are used to denote the same object, which has the reference number 15 in the figures.

The traction/braking machines 15 are connected to the wheels by means of reduction gears. The reduction gear comprises at least one ring gear 16 fixed to a wheel, and a pinion 17 driven by the tractor 15 . The reduction ratio, that is, the ratio between the rotation speed of the tractor and the rotation speed of the wheels, is greater than 10:1. Preferably, the reduction ratio is greater than 15:1. This reduction ratio can be obtained by meshing the pinion 17 directly with the ring gear 16 .

Preferably, however, the reduction means comprise a two-stage reduction, here in the form of a reduction gear 13 applied between a pinion 17 and a ring gear 16 as shown in the figures. The reduction ratio determined by the reduction device is unique and fixed.

The reduction gear 13 consists in this case of two coaxial one-piece toothed wheels 131 and 132, the primary wheel 131 meshing with the pinion 17 of the traction/braking machine, (reduced in size with respect to the primary wheel) Secondary wheel 132 meshes with ring gear 16 . Preferably, the reduction gear 13 is guided relative to the wheel carrier 7 by means of a pair of rolling bearings with tapered rollers 14, and the axial screws 134 absorb the axial component of the forces transmitted by the tapered rolling bearings to their supports.

Preferably, the teeth of the primary wheel, the secondary wheel, the pinion and the ring gear are helical. The angle of the teeth is such that the reduction gears remain reversible, i.e. they can turn in one direction and the other, and also transfer torque from the traction/brakes to the wheels and from the wheels to the traction with acceptable efficiency /brake. Preferably, the angle of the teeth of the primary wheel and the angle of the teeth of the secondary wheel are oriented in the same direction. This characteristic minimizes the axial forces acting on the reduction gear and thus on the wheel carrier.

Preferably, the guiding function for the pinion 17 is performed entirely by the wheel carrier, for example by means of a pair of rolling bearings 18 with balls or rollers. Thus, the pinion comprises its own guiding means, independent of that of the shaft of the traction/braking machine 15 . The pinion is naturally kept driven in rotation by the shaft of the traction/braking machine by means of connection means such as complementary grooves known per se. In this way, the quality of the meshing of the pinion with the ring gear or with the reduction gear is always satisfactory, irrespective of the strength of the transmitted torque, since this is neither due to rigidity nor to traction/braking Efficient guidance of the shaft of the motor. Furthermore, the axial forces acting on the pinion 17 are not transmitted to the shaft of the tractor.

Advantageously, the part forming the ring gear 16 also forms the hub on which the wheel is fixed. To this end, a wheel rolling bearing 6 is arranged in a hole in the central part of the ring gear, and the wheel is screwed to an axial extension 25 of this central part.

Preferably, the rolling bearing 6 is arranged on substantially the same plane as the ring gear 16 . It is understood that this advantageous configuration with regard to the axial space requirement also reduces mass and/or increases stiffness.

Preferably, as shown, the axis of the first machine 15, the axis of the reduction gear 13 and the axis of rotation of the wheel 5 are parallel.

The suspension of the grounded structure according to the invention is a sliding suspension. The wheel carrier is fixed to a generally vertical post 8 . The column can slide relative to the support 10 along its axis 9 by means of guide means 11 , for example with rollers 19 , which are clearly visible in FIG. 6 . This sliding movement corresponds to the suspension clearance of the grounded structure. Preferably, the performance of the suspension is effectively controlled by the second rotary electric machine 12 . In this application, the term "suspension machine" is also used for this second machine. The support 10 is used to connect the grounded structure to the vehicle body rigidly or by means of a connection that allows additional degrees of freedom, such as changes in height of the vehicle body and/or changes in wheel camber angle, filtering vibrations, or horizontal suspension (eg according to the description of patent application EP1616731).

Preferably, the wheel carrier 7 comprises a protruding portion around which the wheel rolling bearing 6 is fitted. Thus, the assembly comprising the wheel and the ring gear is guided around the fixed part of the wheel carrier by this double ball bearing. Thus, the inherent rigidity of the guidance of the wheels is significantly increased compared to the arrangement of application EP0878332 in which the wheel rolling bearings are held in the central opening of the wheel carrier.

The guides 11 of the translationally moving columns 8 are "frictionless", ie they have as little friction as possible. Guidance by rolling bearings is very suitable. The rollers 19 are rotatably mounted on or relative to the guide 11 , cooperating with bearing races formed on the column. Mutual sliding contact surfaces are also conceivable, insofar as they comprise a suitable treatment, or they are sufficiently lubricated. For example, fluid bearings may be used.

The suspension machine 12 acts by means of a suspension pinion 21 on a toothed rack 20 fastened to the column 8 . This arrangement (see in particular FIG. 6 ) has the advantage that it is particularly well suited for effective control of the suspension characteristics and is more accurate than control by direct electric means.

Preferably, a spring 22 (for example a helical spring) acts between the wheel carrier 7 and the guide 11 to absorb part, preferably all, of the reference static load of the vehicle.

Preferably, the axis 9 of the column is positioned approximately on the axis of rotation of the wheel 5 and approximately vertically on the center plane of the wheel, ie the column is well centered with respect to the wheel. An advantage of this arrangement is that it is advantageous for the suspension path and reduces the mechanical stress on the column or its guides.

Furthermore, preferably, the axis 9 of the column also corresponds to the axis of the steering pivot when the wheel is the drive wheel of the vehicle. This is the situation shown here. As can be seen in FIG. 1 , the pivotal connection is provided by a pair of rolling bearings with tapered rollers 23 . These rolling bearings allow the guide 11 to turn relative to the support 10 about a vertical pivot axis, ie about the axis 9 of the column 8 .

When the pivot axis is so positioned, the drive wheels experience only a very low steering torque due to forces applied by the ground.

As is clearly visible in FIG. 3 , the wheel carrier 7 forms the housing that receives all the reduction means (ring gear 16 , pinion 17 and reduction gear 13 ). The housing is closed by a first sealing cover 24 on the side of the spoke 3 and a second sealing cover 24 on the inside. Therefore, all gears are confined within this housing. The housing may contain a suitable lubricant. Also clearly visible in this figure is the assembly of pinion 17 and reduction gear 13 in the housing.

The braking or traction effort available depends on the torque available on the shaft of the traction/braking machine 15, the reduction ratio and the wheel radius. For example, for a traction/brake machine capable of producing 90Nm, a reduction ratio of 17 and a wheel radius of 300mm, the traction or braking force can reach 5100N. With a grip factor of 1, this force is sufficient for 100% of the potential grip using a tire carrying a weight of 5000N. The load and grip conditions are standard for modern passenger cars. However, the sole purpose of this example is to give a level of magnitude and is not intended to limit the type or class of vehicles to which the invention applies. It will be appreciated that this force represents a "tractive force" when acting in the direction of displacement of the vehicle and a "braking force" when acting in a direction opposite to the direction of displacement of the vehicle, regardless of whether the vehicle is shifting in forward or reverse gear. In fact, it is in each case the same force originating from the torque generated by the traction/braking machine 15 . Therefore, the braking power is sufficient to be able to hold the wheels stationary. Obviously, complete immobility of the wheels is not the best way to stop the vehicle, but the purpose of this example is to facilitate the understanding of the invention.

Thus, a four-wheeled vehicle can practically be equipped with four ground contact structures according to the invention and completely dispense with mechanical service brakes. A vehicle according to the invention can also use only two such ground contact structures, if the axle (eg the non-driven axle) is still equipped with conventional brakes. According to the invention, it is also conceivable to use two or more traction/braking machines in each wheel. An advantage of this option may be the possible redundancy of the traction means and, importantly, the braking means.

The figures clearly show the advantages of the invention with regard to the mechanical space requirements of the different elements. The compactness of the ground contact structure according to the invention makes it possible, for example, to use a wheel narrow enough that it does not come into contact with the pavement during parking maneuvers (see FIG. 1 ).

With regard to weight, the advantages offered by the invention are also significant. In particular, the preferred embodiment of the invention is compared with the preferred embodiment of patent application EP0878332 (visible in Figures 1 and 2 of this application). When the suspension path has been increased from 145mm to 170mm and the wheel seat has been increased from 16 inches to 17 inches, a reduction of around 20% in unsprung mass was observed.

Furthermore, there are no conventional mechanical brakes (see discs and calipers in application EP0878332), thereby eliminating the routine work of changing pads and discs, thus significantly simplifying vehicle maintenance. Among the advantages of eliminating conventional hydraulic brakes, one that can be mentioned is the elimination of any residual friction of the pads (which is known to dissipate a considerable portion of the energy required for conventional vehicle braking operations ). An advantage that may also be mentioned is the elimination of the thermal stresses on the ground contact structure of conventional hydraulic brakes and the avoidance of deficiencies associated with powdering from the wear of pads and discs.

Figure 7 shows the principle of a preferred embodiment of the control of the traction and braking machines. The machine 15 is electrically connected to a controller 30 . The controller 30 is connected to means 31 for storing electrical energy, such as battery packs and/or supercapacitors SC. The controller 30 is also connected to means 32 for dissipating electrical energy, such as a resistor 321 submerged in a heat transfer liquid 322 contained in an exchanger 323, which is contained in a circuit not shown here. in the cooling circuit. The accelerator controller 33, the brake controller 34, and the controller 35 for selecting a forward gear or a reverse gear may consider the driver's operation intention. A device 36 for generating electrical energy (eg, a fuel cell FC) may also be directly connected to the controller 30 . A preferred embodiment of this braking/traction control will be described below.

When the driver selects a forward gear and actuates the accelerator pedal 33 , the controller 30 supplies power to the machine 15 from the storage device 31 or the generating device 36 so that the vehicle can move in a forward direction. Thus, the machine converts electrical energy into mechanical rotational energy. The achieved power depends in particular on the position of the accelerator controller. When the driver actuates the brake pedal 34, the controller 30 stops power to the machine and reverses its operation so the machine converts mechanical rotational energy to electrical energy. This energy can be absorbed by the storage means 31 or by the dissipation means 32 or by both means simultaneously or sequentially.

The storage device 31 and the dissipating device 32 form an absorption device 40 for the electrical energy generated by the braking/tracting machine. The distribution of absorbed energy between storage and dissipation can vary. It can be clearly understood that when the storage device is full, 100% of the energy must be dissipated. Furthermore, the power of the storage means can be limited, ie the loading speed of the storage means can for example correspond to a slight braking, as is currently desired for heat engines (called "engine braking"). Outside this braking level, the electrical energy generated is sent directly to the dissipation device.

When the driver selects Reverse, the controller 30 may power the machine 15 in a similar manner to the Drive, but reverse rotation (including under braking).

The description that has been made is limited to the control of one traction/braking machine. In practice, the same principle can be used to control multiple traction/braking machines, each driving a wheel. This control can take into account additional criteria, such as the speed or slip of the wheels, to limit and/or distribute traction/braking forces in the best possible way on all wheels, thus being implemented electrically to help drive (ABS, ESP) with High precision function.

Claims (13)

1. a ground structure that is used for vehicle, comprising: wheel (1), the slip suspension that is used for wheel carrier with respect to the strut member that is connected to vehicle (10) slip, described suspension comprises the roughly vertical post (8) that is fixed to wheel carrier, wheel carrier allows by the motion of post in guiding device (11) with respect to the degree of freedom of the suspension of strut member (10), and described guiding device (11) is connected to strut member, and the device that is used for driving by the first rotating machine (15) that is arranged on wheel wheel, the first rotating machine drives wheel by means of reversible speed reduction gearing, described speed reduction gearing comprises the Ring gear (16) that is fixed to wheel, with the Drive pinion that is connected to the first rotating machine (17), and limit the reduction ratio between the velocity of rotation of the velocity of rotation of the first rotating machine and wheel, it is characterized in that, described reduction ratio is greater than 10, described ground structure does not have mechanical pedal brake, described speed reduction gearing comprises double reduction, described speed reduction gearing comprises reducing gear (13), described reducing gear (13) coordinates with Drive pinion (17) on the one hand, on the other hand be fixed to wheel on Ring gear (16) coordinate, and reducing gear (13) comprises that two coaxial integral types are toothed and takes turns (131, 132).

2. ground structure as claimed in claim 1, is characterized in that, reduction ratio is greater than 15.

3. ground structure as claimed in claim 1 or 2, is characterized in that, two toothed teeth of taking turns are spiral fashion and directed along identical direction.

4. ground structure as claimed in claim 1, is characterized in that, the pivot center of the first rotating machine (15) is parallel with the axis (5) of wheel.

5. ground structure as claimed in claim 1, is characterized in that, Drive pinion (17) has helical tooth, and with the axle of the first rotating machine independently mode by the axis guiding with respect to wheel.

6. ground structure as claimed in claim 1, it is characterized in that, the a pair of antifriction-bearing box (6) that is guided through to the runner assembly that comprises wheel (1) and Ring gear (16) provides, and described a pair of antifriction-bearing box (6) is set on the projection of wheel carrier (7).

7. ground structure as claimed in claim 1, is characterized in that, it comprises that also described the second rotating machine is fixed to guiding device (11) for the second rotating machine (12) of controlling the suspension motion; And the suspension miniature gears (21) that is driven by the second rotating machine, described suspension miniature gears coordinates with tooth bar (20) on being fixed to post (8).

8. ground structure as claimed in claim 1, is characterized in that, the axis of post (9) roughly is positioned on the centre plane of wheel, and crossing with the pivot center (5) of wheel.

9. ground structure as claimed in claim 1, is characterized in that, it also comprises the hinge connector (23) with respect to the guiding device (11) of strut member (10) guiding, turns to around pivot axis to allow wheel.

10. ground structure as claimed in claim 9, is characterized in that, pivot axis is roughly corresponding with the axis (9) of post.

11. a vehicle, described vehicle comprise according to arbitrary described ground structure in the claim of front, it also comprises for the absorption plant (40) that absorbs electric energy, and described absorption plant can absorb the electric energy by the first rotating machine generation in braking procedure.

12. vehicle as claimed in claim 11 is characterized in that, absorption plant comprises resistor (321), and described resistor (321) is immersed in the pond of heat transfer fluid body (322).

13. vehicle as described in claim 11 or 12, it is characterized in that, absorption plant comprises the device (31) for store electrical energy, and described device for store electrical energy (31) can store at braking procedure the part of the electric energy that is produced by the first rotating machine.

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